JP5493529B2 - Conductive member, charging device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a conductive member, a charging device, a process cartridge, and an image forming apparatus.

  In recent years, image forming apparatuses such as printers and copiers have been widely used, and technologies relating to various elements constituting the image forming apparatus have also been widely used. Among image forming apparatuses that employ an electrophotographic method, a photosensitive member such as a photosensitive member (image holding member) drum is charged by using a charging device, and an ambient potential is applied on the charged photosensitive member. In many cases, a pattern to be printed is formed by forming an electrostatic latent image having a potential different from that of the electrostatic latent image. The electrostatic latent image formed in this way is developed with toner, and finally recorded. It is transferred onto a recording medium such as paper.

  For example, Patent Document 1 states that “in the contact charging member for a charging device, the specific surface area of N-methoxymethylated nylon in the layer in contact with the member to be charged is 700 to 1600 m 2 / g, and the oil absorption (DBP) is 150 to 550 cc. The cross-linking degree of the N-methoxymethylated nylon of the charging member using the surface layer in which 100 g of carbon black is dispersed is 100.24 or less, and the average secondary particle size of the carbon black after dispersion 1.0 to 5.0 μm, wherein the carbon black is added in an amount of 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the N-methoxymethylated nylon resin. A contact charging member characterized by being in the range of "is proposed.

  Patent Document 2 includes “polyamide (A), modified polyolefin and / or hydrogenated product of butadiene / styrene copolymer (B), polyolefin (C) contained if necessary, and carbon black (D). In the sea-island structure formed of a plurality of synthetic resins, the polyamide (A) forms a sea portion, and the average diameter of the island portions formed of the synthetic resin other than the polyamide (A) is 5 μm or less. A polyamide-based electrophotographic member characterized in that it has been proposed.

Japanese Patent Laid-Open No. 08-137186 Japanese Patent Laid-Open No. 2004-210828

  The subject of this invention is providing the electroconductive member by which the discharge which suppressed the discharge nonuniformity by a small electric current value is implement | achieved compared with the case where it does not have a surface layer with the following specific sea island structure.

The above problem is solved by the following means. That is,
The invention according to claim 1
A substrate;
An elastic layer disposed on a substrate;
It has a sea-island structure which is disposed on the elastic layer and includes a sea part including a first resin and an island part including a second resin, and at least carbon black is included in the island part. Of the carbon black contained in the island part, 90% of the carbon black present in the region 50 nm inside from the interface between the island part and the sea part is 90% of the total carbon black contained in the island part. % Or more surface layer,
A conductive member having

The invention according to claim 2
The conductive member according to claim 1, wherein the island portion has a diameter of 100 nm to 500 nm.

The invention according to claim 3
3. The conductive member according to claim 1, wherein the amount of carbon black contained in the island portion is 90% or more with respect to the total carbon black contained in the surface layer.

The invention according to claim 4
A charging device including a conductive member according to any one of claims 1-3.

The invention according to claim 5
An image carrier, and charging means for charging the image carrier,
5. A process cartridge, wherein the charging means is the charging device according to claim 4 .

The invention according to claim 6
An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
With
The image forming apparatus, wherein the charging unit is the charging device according to claim 4 .

According to the first aspect of the present invention, compared to the case where the surface layer having the specific sea-island structure is not provided, a discharge in which discharge unevenness is suppressed with a small current value is realized.
According to the invention which concerns on Claim 2, compared with the case where the diameter of an island part is outside the said range, the discharge which suppressed discharge nonuniformity with a small electric current value is implement | achieved.
According to the invention of claim 3, the discharge unevenness is suppressed with a small current value compared to the case where the amount of carbon black contained in the island portion is outside the above range with respect to the total carbon black contained in the surface layer. Discharging is realized.
According to the first aspect of the present invention, compared to a case where the carbon black contained in the island portion is not unevenly distributed on the interface side between the island portion and the sea portion, a discharge in which discharge unevenness is suppressed with a small current value is realized.
According to the fourth aspect of the present invention, charging with less current unevenness can be realized with a smaller current value than when a conductive member having a specific sea-island structure and no surface layer is applied.
According to the invention which concerns on Claim 5 , compared with the case where the electroconductive member which does not have the surface layer which has the said specific sea island structure is applied, the image by which the white point was suppressed is obtained.
According to the invention which concerns on Claim 6 , compared with the case where the electroconductive member which does not have the surface layer which has the said specific sea island structure is applied, the image by which the white point was suppressed is obtained.

It is a schematic perspective view which shows the charging member which concerns on this embodiment. It is a schematic sectional drawing of the charging member which concerns on this embodiment. It is an expanded sectional view which shows the surface layer in the charging member which concerns on this embodiment. 1 is a schematic perspective view of a charging device according to an embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment. 2 is a view showing a transmission microscope (TEM) photograph of a surface layer sample of a charging roll produced in Example 1. FIG.

  Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.

(Conductive member)
FIG. 1 is a schematic perspective view showing a conductive member according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the conductive member according to the present embodiment. FIG. 3 is an enlarged cross-sectional view showing a surface layer in the conductive member according to the present embodiment. 2 is a cross-sectional view taken along the line AA in FIG.

As shown in FIGS. 1 and 2, the conductive member 121 </ b> A according to the present embodiment includes, for example, a shaft 30 (an example of a base material), an elastic layer 31 disposed on the outer peripheral surface of the shaft 30, and an elastic layer. And a surface layer 32 disposed on the outer peripheral surface of 31.
The surface layer 32 has a sea-island structure including a sea portion 33A including the first resin and an island portion 33B including the second resin, and at least the carbon black 34 inside the island portion 33B. It is comprised including.

The conductive member 121 </ b> A according to the present embodiment is not limited to the above configuration, for example, an adhesive layer (primer layer) disposed between the elastic layer 31 and the shaft 30, and between the elastic layer 31 and the surface layer 32. A configuration may be provided in which a resistance adjusting layer or a transition prevention layer disposed on the surface layer 32 and a coating layer (protective layer) disposed on the outer side (outermost surface) of the surface layer 32 are provided.
Moreover, although the roll-shaped member is described in the conductive member 121A according to the present embodiment, it is not limited to this, and may be an endless belt-shaped member or a sheet-shaped member.

  Hereinafter, each member of the conductive member 121A according to the present embodiment will be described.

The shaft will be described.
The shaft 30 is a conductive rod-like member, and examples of the material thereof include metals such as iron (free-cutting steel), copper, brass, stainless steel, aluminum, nickel, and the like. Examples of the shaft 30 include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The shaft 30 may be a hollow member (cylindrical member) or a non-hollow member. Here, the conductivity means that the volume resistivity is less than 10 ¹³ Ωcm.

The elastic layer will be described.
The elastic layer 31 includes, for example, an elastic material, a conductive agent, and other additives as necessary.

  Elastic materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide- Examples include allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and blend rubbers thereof. Among these, polyurethane, silicone rubber, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and blended rubbers thereof are desirably used. These elastic materials may be foamed or non-foamed.

  Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide And various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium; perchlorates and chlorates of alkaline earth metals ; These conductive agents may be used alone or in combination of two or more.

  Here, specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Special Black 550”, “Special Black 6”, “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “MONARCH1000” manufactured by Cabot, Cabot “MONARCH1300” manufactured by Cabot Corporation, “MONARCH1400” manufactured by Cabot Corporation, “MOGUL-L”, “REGAL400R”, etc.

  The addition amount of the conductive agent is not particularly limited, but in the case of the electronic conductive agent, it is preferably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the elastic material. It is more desirable that the amount be in the range of parts by mass or less. On the other hand, in the case of the ionic conductive agent, it is desirable that the amount be in the range of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the elastic material, and 0.5 to 3.0 parts by weight. The following range is more desirable.

  Examples of other additives blended in the elastic layer 31 include a softener, a plasticizer, a curing agent, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a surfactant, a coupling agent, and a filler (silica, Examples thereof include materials that can be added to a normal elastic layer such as calcium carbonate).

The thickness of the elastic layer 31 is preferably about 1 mm to 10 mm in terms of average film thickness, and more preferably about 2 mm to 5 mm. The volume resistivity of the elastic layer is preferably 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less.

The surface layer will be described.
As shown in FIG. 3, the surface layer 32 has a sea-island structure including a sea portion 33 </ b> A that includes the first resin and an island portion 33 </ b> B that includes the second resin. The island portion is configured to include carbon black 34.

In the sea-island structure, the diameter of the island portion 33B is, for example, preferably 100 nm to 500 nm, and more preferably 150 nm to 400 nm. By setting the diameter within the above range, the carbon black is easily contained in the island portion 33B as an aggregate having an appropriate size. As a result, the conductive member 121A realizes discharge with suppressed discharge unevenness with a small current value.
In addition, the diameter of the island portion is prepared by preparing a sample (slice) of the surface layer 32 by the cryomicome method, and observing this sample with a transmission electron microscope (TEM) to determine the maximum diameter of the ten island portions 33B. Measure and take this average value.

Here, the “sea-island structure” is a structure in which at least two resins (first resin and second resin) are mixed with each other in an incompatible state, and a continuous phase made of one of the first resins is the sea portion 33A, The structure which makes the discontinuous phase which consists of the other 2nd resin which exists in the suspended state in the sea part 33A used as a continuous phase the island part 33B is meant.
Further, the sea-island structure has a solubility parameter (SP value) ratio between the first resin and the second resin (SP value of the first resin constituting the sea part 33A / SP value of the second resin constituting the island part 33B), It is formed by adjusting the mixing ratio of the first resin and the second resin. When the SP value ratio between the first resin and the second resin is large, it is easy to form a sea-island structure.

Specifically, the SP value difference between the first resin and the second resin is preferably 2 or more and 10 or less, for example. When the SP value difference is within the above range, a sea-island structure is easily formed.
The mixing ratio (mass ratio: first resin / second resin) of the first resin and the second resin is, for example, preferably 98/2 to 75/25, and desirably 95 / to 85/15. It is. When this mixing ratio is in the above range, a sea-island structure having an appropriately large island portion (for example, an island portion having a diameter in the above range) is easily formed.

In addition, the calculation method of a solubility parameter (SP value) uses the method described in "Polymer handbook 4th edition John Wiley &Sons" VII680-683. The solubility parameter (SP value) is a value obtained by multiplying the aggregation energy density, that is, the evaporation energy per unit volume of one molecule to the half power, and indicating the magnitude of polarity per unit volume.
In the case of a resin, calculation is generally made using the following small formula.
Formula: SP (cal / cm ³ ) ^1/2 = dΣG / M
(Where, M: unit molecular weight of polymer, d: density, G: constant specific to atomic group / group)
The main resin solubility parameters are described in VII 702-711 of the Polymer Handbook 4th edition. As the solubility parameter, a value derived by substituting the cohesive energy constant of Hoy into the above-described small formula may be adopted.

  On the other hand, in order to include the carbon black 34 inside the island portion 33B, for example, a resin type in which the carbon black 34 is difficult to disperse is selected as the first resin constituting the sea portion 33A, and the second portion constituting the island portion 33B is selected. It is preferable to select a resin type in which the carbon black 34 is easily dispersed as the resin.

Examples of the first resin constituting the sea part include acrylic resin, cellulose resin, polyamide resin, copolymer nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, styrene butadiene resin, and melamine resin. Epoxy resin, urethane resin, silicone resin, fluororesin (for example, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, etc.), urea resin, etc. . Here, the copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and other polymer units included in the copolymer include: , 6 nylon, 66 nylon and the like. Moreover, you may apply the elastic material mix | blended with the said elastic layer 31 as 1st resin.
In addition, as 1st resin, you may use 2 or more types of resin together.

  As 2nd resin which comprises the island part 33B, polyvinyl butyral resin (PVB), a polystyrene resin, polyvinyl alcohol, etc. are mentioned, for example.

  Examples of the carbon black 34 include ketjen black, acetylene black, and oxidized carbon black having a pH of 5 or less. Specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4”, and “Special Black 4” manufactured by Degussa. "Special Black 4A", "Special Black 550", "Special Black 6", "Color Black FW200", "Color Black FW2", "Color Black FW2V", "MONARCH1000" manufactured by Cabot, manufactured by Cabot “MONARCH 1300”, “MONARCH 1400” manufactured by Cabot Corporation, “MOGUL-L”, “REGAL 400R”, and the like can be given.

The DBP oil absorption amount of the carbon black 34 is, for example, preferably 80 cc / 100 g or more and 160 cc / 100 g or less, and desirably 90 cc / 100 g or more and 120 cc / 100 g or less. When the oil absorption is in the above range, the carbon black 34 is likely to be contained in the island portion 33B as an appropriately sized aggregate (aggregate having an average particle size in the following range). As a result, the conductive member 121 </ b> A realizes discharge with suppressed discharge unevenness with a small current value.
The DBP oil absorption (cc / 100 g) indicates the amount of dibutyl phthalate (DBP) absorbed by 100 g of carbon black, and is a value defined in ASTM (American Standard Test Method) D2414-6TT. .

The carbon black 34 is preferably unevenly distributed on the interface side between the island portion 33B and the sea portion 33A and is included in the island portion 33B. As a result, the carbon black 34 is likely to be contained in the island portion 33B as an aggregate having an appropriate size. As a result, the conductive member 121 </ b> A realizes discharge with suppressed discharge unevenness with a small current value.
Specifically, as the degree of uneven distribution, the carbon black 34 existing in the region 50 nm inside from the interface between the island portion 33B and the sea portion 33A (its abundance ratio) is based on the total carbon black 34 included in the island portion 33B. 90% or more is good.
The existence ratio of the unevenly distributed carbon black is determined by preparing a sample (slice) of the surface layer 32 by the cryomicome method and observing the island portion 33B with a transmission electron microscope (TEM). The area of the carbon black 34 contained in 33B and the carbon black 34 that is unevenly distributed on the interface side between the sea portion 33A and the island portion 33B is measured and calculated, and this is the average value obtained at 10 locations.

The content of carbon black 34 (content of the total carbon black contained in the surface layer 32) is, for example, preferably 10% by mass or more and 20% by mass or more, and more preferably 13% by mass or more and 16% by mass or less.
However, the amount (presence) of carbon black contained in the island portion 33B is preferably 90% or more (preferably 90% or more) with respect to the total carbon black contained in the surface layer 32. By setting the content within the above range, since the amount of carbon black 34 contained in the sea is small, the conductive member 121A can achieve discharge with suppressed discharge unevenness with a small current value.
The abundance of carbon black contained in the island portion 33B is determined by preparing a sample (section) of the surface layer 32 by the cryo-mictome method, and using this sample for the sea portion 33A and the island portion by a transmission electron microscope (TEM). The area of carbon black existing in each of the sea part 33A and the island part 33B is measured and calculated by observing a 4 μm × 4 μm square including the part 33B, and this is the average value obtained for 10 locations.

The thickness (overall thickness) of the surface layer 32 is preferably 7 μm or more and 25 μm or less in terms of average film thickness. The volume resistivity of the surface layer is preferably 10 ³ Ωcm or more and 10 ¹⁴ Ωcm or less.

  The conductive member 121A according to the present embodiment is formed on the outer peripheral surface of the shaft 30, for example, by a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, a curtain, for example. The elastic layer 31 and the surface layer 32 are sequentially formed on the outer peripheral surface of the shaft 30 using a coating method or the like.

The conductive member 121A according to the present embodiment described above has a sea-island structure including a sea portion 33A including the first resin and an island portion 33B including the second resin, and at least the island portion. A surface layer 32 including carbon black 34 is provided inside 33B. Thereby, the discharge which suppressed discharge nonuniformity with a small electric current value is realized. This is also maintained for a long time.
The reason is not clear, but is presumed to be due to the following reason. The island 33B, which is a discontinuous phase in the sea-island structure, is contained in the sea portion 33A, which is a continuous phase, in a dispersed state without being unevenly distributed in a specific size. Therefore, carbon black 34 is contained inside the island 33B. By configuring so as to be included, the carbon black 34 is considered to be included in the surface layer 32 as an agglomerate of an appropriate size without being unevenly distributed with the island portion 33B. In other words, the carbon black 34 that is included in the island portion 33B using the sea-island structure of the resin is in a state of large aggregates that are likely to become the starting point of abnormal discharge or in a state of primary particles that are likely to cause discharge unevenness. However, it is considered that the agglomerates having an appropriate size controlled by the size of the islands are included in the surface layer 32 without variation. For this reason, it is considered that the conductive member 121A having the surface layer 32 containing the carbon black 34 in such a state realizes discharge with suppressed discharge unevenness with a small current value, and maintains this for a long time.

The conductive member 121A according to the present embodiment is applied to, for example, a conductive member (for example, a charging roll), a transfer member (for example, a transfer roll) in an electrophotographic image forming apparatus.
For example, when the conductive member 121A according to the present embodiment is applied to a charging member, charging that suppresses uneven charging with a small current value is realized, and charging unevenness is achieved in an image forming apparatus (or process cartridge) including the charging member. An image in which the occurrence of white spots due to the above is suppressed is obtained.
Further, for example, when the conductive member 121A according to the present embodiment is applied to a transfer member, transfer that suppresses transfer unevenness with a small current value is realized, and an image forming apparatus (or process cartridge) including the charging member An image in which image defects due to transfer unevenness are suppressed is obtained.

(Charging device)
Hereinafter, the charging device according to the present embodiment will be described. FIG. 4 is a schematic perspective view of the charging device according to the present embodiment. The charging device according to the present embodiment is a form in which the conductive member according to the present embodiment is applied as a charging member.

  As shown in FIG. 4, the charging device 12 according to the present embodiment is arranged such that, for example, the charging member 121 and the cleaning member 122 are in contact with each other with a specific biting amount. The axial ends of the shaft 30 of the charging member 121 and the shaft 122A of the cleaning member 122 are held by conductive bearings 123 (conductive bearings) so that the respective members can rotate. A power supply 124 is connected to one of the conductive bearings 123. Note that the charging device according to the present embodiment is not limited to the above-described configuration, and may be a form that does not include the cleaning member 122, for example.

  The cleaning member 122 is a cleaning member for cleaning the surface of the charging member 121, and is configured in a roll shape, for example. The cleaning member 122 includes, for example, a shaft 122A and an elastic layer 122B on the outer peripheral surface of the shaft 122A.

  The shaft 122A is a conductive rod-like member, and examples of the material thereof include metals such as iron (free-cutting steel and the like), copper, brass, stainless steel, aluminum, and nickel. Examples of the shaft 122A include a member (for example, a resin or a ceramic member) whose outer peripheral surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like. The shaft 122A may be a hollow member (cylindrical member) or a non-hollow member.

  The elastic layer 122B is made of a foam having a porous three-dimensional structure. The elastic layer 122B preferably has elasticity, with cavities and concavo-convex portions (hereinafter referred to as cells) inside and on the surface. The elastic layer 122B is made of polyurethane, polyethylene, polyamide, olefin, melamine or polypropylene, NBR (acrylonitrile-butadiene copolymer rubber), EPDM (ethylene-propylene-diene copolymer rubber), natural rubber, styrene butadiene rubber, chloroprene, silicone, It includes a foamable resin material such as nitrile or a rubber material.

  Among these foamable resin materials or rubber materials, foreign substances such as toner and external additives are efficiently cleaned by driven sliding friction with the charging member 121, and at the same time, the cleaning member 122 is formed on the surface of the charging member 121. In order to prevent scratches due to rubbing and to prevent tearing and breakage from occurring over a long period of time, polyurethane that is strong against tearing and tensile strength is particularly preferably applied.

  The polyurethane is not particularly limited. For example, polyol (for example, polyester polyol, polyether polyester, acrylic polyol, etc.) and isocyanate (2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4, 4-diphenylmethane diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, etc.), and reaction products of these chain extenders (eg, 1,4-butanediol, trimethylolpropane, etc.) Good. Polyurethane is generally foamed using a foaming agent (water or an azo compound (azodicarbonamide, azobisisobutyronitrile, etc.).

  The number of cells per 25 mm (number / 25 mm) of the elastic layer 122B is preferably 20/25 mm or more and 80/25 mm or less, more preferably 30/25 mm or more and 80/25 mm or less, and 30/25 mm or more. It is particularly desirable that it is 50/25 mm or less.

  The hardness of the elastic layer 122B is preferably 100N to 500N, more preferably 100N to 400N, and particularly preferably 150N to 400N.

  The conductive bearing 123 is a member that holds the charging member 121 and the cleaning member 122 integrally and rotatably, and also holds an inter-axis distance between the members. The conductive bearing 123 may be of any material and form as long as it is made of a conductive material. For example, a conductive bearing or a conductive sliding bearing is applied.

  The power supply 124 is a device that charges the charging member 121 and the cleaning member 122 to the same polarity by applying a voltage to the conductive bearing 123, and a known high-voltage power supply device is employed.

  In the charging device 12 according to the present embodiment, the charging member 121 and the cleaning member 122 are charged to the same polarity by applying a voltage from the power source 124 to the conductive bearing 123. As a result, foreign matter (for example, toner or external additives) on the surface of the image carrier is prevented from accumulating on the surfaces of the cleaning member 122 and the charging member 121 and can be transferred to the image carrier, and the foreign matter is collected by the image carrier cleaning device. Is done. Therefore, accumulation of dirt on the charging member 121 and the cleaning member 122 is suppressed over a long period of time, and charging performance is maintained.

(Image forming device, process cartridge)
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and the image carrier. Developing means for developing the latent image formed on the surface of the toner image with toner to form a toner image, and transfer means for transferring the toner image formed on the surface of the image carrier to a recording medium. The charging device according to the present embodiment is applied as the charging means (charging device).

  On the other hand, the process cartridge according to this embodiment includes, for example, an image holding member that is detached from the image forming apparatus having the above-described configuration, and a charging unit that charges the image holding member. The charging device according to the present embodiment is applied as the charging unit. The process cartridge according to the present embodiment includes, as necessary, developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image, and a toner image formed on the surface of the image carrier. At least one selected from the group consisting of a transfer unit that transfers the toner to a recording medium and a cleaning unit that removes residual toner on the surface of the image carrier after transfer.

  Next, an image forming apparatus and a process cartridge according to the present embodiment will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram illustrating the image forming apparatus according to the present embodiment. FIG. 6 is a schematic configuration diagram showing a process cartridge according to the present embodiment.

  As shown in FIG. 5, the image forming apparatus 101 according to the present embodiment includes an image carrier 10, a charging device 12 that charges the image carrier around the image carrier 10, and an image carrier charged by the charging device 12. An exposure device 14 that exposes 10 to form a latent image, a developing device 16 that develops the latent image formed by the exposure device 14 with toner to form a toner image, and a toner image that is formed by the developing device 16 A transfer device 18 for transferring to A, and a cleaning device 20 for removing residual toner on the surface of the image carrier 10 after transfer. Further, a fixing device 22 for fixing the toner image transferred to the recording medium A by the transfer device 18 is provided.

  The image forming apparatus 101 according to the present embodiment includes, as the charging device 12, for example, a charging member 121, a cleaning member 122 disposed in contact with the charging member 121, and both axial ends of the charging member 121 and the cleaning member 122. The charging device according to the present embodiment, in which a conductive bearing 123 (conductive bearing) that holds each member so as to be rotatable and a power source 124 connected to one of the conductive bearings 123 are disposed. Has been applied.

  On the other hand, in the image forming apparatus 101 of the present embodiment, known configurations are conventionally applied as the components of the electrophotographic image forming apparatus, except for the charging device 12 (charging member 121). Hereinafter, an example of each configuration will be described.

  The image carrier 10 is not particularly limited, and a known photoreceptor can be used. An organic photoreceptor having a so-called function separation type structure in which a charge generation layer and a charge transport layer are separated is preferably used. In addition, the image carrier 10 is preferably applied to a photoconductor whose surface layer is made of a siloxane resin or a phenol resin having a charge transporting property and a crosslinked structure.

  As the exposure apparatus 14, for example, a laser optical system, an LED array, or the like is applied.

  For example, the developing device 16 brings a toner image onto the latent image on the surface of the image carrier 10 by bringing a developer carrier having a developer layer formed on the surface thereof into contact with or close to the image carrier 10. A developing device to be formed. As a developing method of the developing device 16, a developing method using a two-component developer is suitably applied as a known method. Examples of the developing method using the two-component developer include a cascade method and a magnetic brush method.

  Examples of the transfer device 18 include a non-contact transfer method such as corotron and scorotron, and a contact transfer method in which a conductive transfer roll is brought into contact with the image carrier 10 via the recording medium A to transfer a toner image to the recording medium A. Either may be applied.

  The cleaning device 20 is, for example, a member that removes toner, paper dust, dust, and the like adhering to the surface by bringing a cleaning blade into direct contact with the surface of the image carrier 10. As the cleaning device 20, a cleaning brush, a cleaning roll, or the like may be applied in addition to the cleaning blade.

  As the fixing device 22, a heat fixing device using a heat roll is suitably applied. The heat fixing device includes, for example, a fixing roller in which a so-called release layer is formed of a heat-resistant resin coating layer or a heat-resistant rubber coating layer on the outer peripheral surface thereof with a heater lamp for heating inside a cylindrical metal core, A pressure roller or a pressure belt that is disposed in contact with the fixing roller at a specific contact pressure and has a heat-resistant elastic body layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. . The fixing process of the unfixed toner image is performed, for example, by inserting the recording medium A onto which the unfixed toner image is transferred between a fixing roller and a pressure roller or a pressure belt, and binding resin in the toner, Fixing by heat melting of additives and the like.

  The image forming apparatus 101 according to the present embodiment is not limited to the above configuration. For example, an intermediate transfer type image forming apparatus using an intermediate transfer member and an image forming unit that forms toner images of each color are arranged in parallel. A so-called tandem image forming apparatus may be used.

  On the other hand, as shown in FIG. 6, the process cartridge according to the present embodiment includes an opening 24A for exposure, an opening 24B for static elimination exposure, and a mounting rail 24C in the image forming apparatus shown in FIG. By the housing 24, the image carrier 10, the charging device 12 for charging the image carrier, the developing device 16 for developing the latent image formed by the exposure device 14 with toner and forming a toner image, and after the transfer And a cleaning device 20 that removes residual toner on the surface of the image holding body 10 and is integrally assembled and held. The process cartridge 102 is detachably attached to the image forming apparatus 101 shown in FIG.

  In the image forming apparatus according to the present embodiment, the embodiment in which the conductive member according to the present embodiment is provided as the charging device (the charging member) has been described. However, the book as the transfer device (the transfer member) is described. The form provided with the electroconductive member which concerns on embodiment may be sufficient.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by the following Example. Unless otherwise specified, “part” means “part by mass”.

[Example 1]
(Preparation of charging roll)
-Formation of elastic layer-
Elastic material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber) 15 parts by mass of conductive agent (carbon black Asahi Thermal: manufactured by Asahi Carbon Co., Ltd.) and vulcanizing agent (sulfur 200 mesh: Tsurumi Chemical Co., Ltd.) 1 part by mass, and vulcanization accelerator (Noxeller DM: manufactured by Ouchi Shinsei Chemical Co., Ltd.): a mixture of 2.0 parts by mass and the like is kneaded with an open roll, and a shaft made of SUS303 and having a diameter of 8 mm. (Conductive support) An elastic layer having a thickness of 7 mm was formed on the outer peripheral surface of the outer peripheral surface through an adhesive layer using a press molding machine to obtain a roll having a diameter of 15 mm. Thereafter, a conductive elastic roll having a diameter of 14 mm having an elastic layer having a thickness of 6 mm was obtained by polishing.

-Formation of surface layer-
As a first resin, 100 parts by mass of a nylon resin solution (nylon resin solution: solid content concentration 8% by mass) obtained by dissolving nylon resin in a mixed solution of methanol and 1-butanol (mixing mass ratio = methanol: 1-butanol = 3: 1) On the other hand, 10 parts by mass of polyvinyl butyral resin (PVB), 12 parts by mass of carbon black (trade name “MONARCH880” manufactured by Cabot) and 2 parts by mass of a curing agent (citric acid) are added as a second resin. And this was diluted with methanol to obtain a dispersion. Then, the dispersion was dip-coated on the surface of the conductive elastic roll and dried by heating at 160 ° C. for 20 minutes to form a surface layer having a thickness of 10 μm. Details of the materials used are shown in Table 1.
In this way, a charging roll was obtained.

[Examples 2-6, Comparative Examples 1-2]
A charging roll was obtained in the same manner as in Example 1 except that the first resin, the second resin, and carbon black were changed according to Table 1.

[Evaluation of charging roll]
-Surface layer characteristics-
As described above, with a transmission microscope (TEM), the presence or absence of a sea-island structure, the diameter of the island, the ratio of the carbon black contained in the island to the total carbon black contained in the surface layer (in Table 1, island CB abundance ratio), average particle size of carbon black aggregates contained in islands (indicated as CB aggregate average particle size in Table 1), carbon black contained in islands is the interface side between islands and seas (Table 1 indicates the presence / absence of CB uneven distribution). The results are shown in Table 1.
A transmission microscope (TEM) photograph of the surface layer of the charging roll produced in Example 1 is shown in FIG. In the TEM photograph of FIG. 7, a region that is a whitish discontinuous phase indicates an island portion, and a black dotted region indicates carbon black.
From FIG. 7, it can be seen that in the surface layer of the charging roll, carbon black is contained inside the island portion and is unevenly distributed on the interface side between the island portion and the sea portion.

-Evaluation of charging characteristics-
The process roller of Fuji Xerox color copier DocuCenter Color a450 is assembled with the manufactured charging roll, and the halftone (image density 50) is changed while changing the current value as shown in Table 2 in an environment of temperature 10 ° C. and humidity 15%. %). If no white spots were generated due to uneven charging due to the charging roll, ◎ if 10 or less, Δ if 30 or less, and × if more. The results are shown in Table 2.

  From the above results, it can be seen that in this example, even when the current value is small, the discharge unevenness is suppressed and the occurrence of white spots due to this is suppressed even when the current value is small.

DESCRIPTION OF SYMBOLS 10 Image carrier, 12 Charging device, 14 Exposure device, 16 Developing device, 18 Transfer device, 20 Cleaning device, 22 Fixing device, 24 Housing, 24A Opening, 24B Opening, 24C Mounting rail, 30 Shaft, 31 Elasticity Layer, 32 surface layer, 33A sea part, 33B island part, 101 image forming apparatus, 102 process cartridge, 121 charging member, 121A conductive member, 122 cleaning member, 123 conductive bearing, 122A shaft, 122B elastic layer, 124 power supply

Claims (6)

A substrate;
An elastic layer disposed on a substrate;
It has a sea-island structure which is disposed on the elastic layer and includes a sea part including a first resin and an island part including a second resin, and at least carbon black is included in the island part. Of the carbon black contained in the island part, 90% of the carbon black present in the region 50 nm inside from the interface between the island part and the sea part is 90% of the total carbon black contained in the island part. % Or more surface layer,
A conductive member having   The conductive member according to claim 1, wherein the island portion has a diameter of 100 nm to 500 nm.   3. The conductive member according to claim 1, wherein the amount of carbon black contained in the island portion is 90% or more with respect to the total carbon black contained in the surface layer.   A charging device comprising the conductive member according to claim 1. An image carrier, and charging means for charging the image carrier,
5. A process cartridge, wherein the charging means is the charging device according to claim 4. An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier to a recording medium;
With
The image forming apparatus, wherein the charging unit is the charging device according to claim 4.